Thursday, 28 January 2016

Yowah Opal

Yowah is a small town in outback western Queensland, Australia. Yowah is located 938 kilometres west of Brisbane and 132 kilometres west of Cunnamulla. The 2006 census revealed a population of 142.

The town is famous for its opal mining and numerous opal fields that lie around the town as well as the "Yowah Nut" a local type of opal distinctive to the region. The area was first leased in 1883 to perspective settlers and opal mining has been the main activity ever since.

The Yowah field is an occurrence of opal in siliceous ironstone nodules generally referred to as Yowah Nuts. These nuts have a spherical or ellipsoidal shape, and show alternate bands of light and dark-brown siliceous ironstone. There is sometimes a kernel of precious opal, which is the main source of the gem.

The nuts are found in layers (150–600mm in thickness) at depths up to 20m in a ferruginous sandstone, and are commonly associated with mudstone fragments or clay pellets.